GRASS logo

Note: A new GRASS GIS stable version has been released: GRASS GIS 7, available here. And see the new manual page here

NAME

v.normal - Tests for normality for points.

KEYWORDS

vector, statistics

SYNOPSIS

v.normal
v.normal help
v.normal [-rql] map=string tests=range[,range,...] column=string [--verbose] [--quiet]

Flags:

-r
Use only points in current region
-q
Quiet
-l
lognormal
--verbose
Verbose module output
--quiet
Quiet module output

Parameters:

map=string
point vector defining sample points
tests=range[,range,...]
Lists of tests (1-15): e.g. 1,3-8,13
column=string
Attribute column

DESCRIPTION

v.normal computes tests of normality on vector points.

NOTES

The tests that v.normal performs are indexed below. The tests that are performed are specified by giving an index, ranges of indices, or multiple thereof.
  1. Sample skewness and kurtosis
  2. Geary's a-statistic and an approximate normal transformation
  3. Extreme normal deviates
  4. D'Agostino's D-statistic
  5. Modified Kuiper V-statistic
  6. Modified Watson U^2-statistic
  7. Durbin's Exact Test (modified Kolmogorov)
  8. Modified Anderson-Darling statistic
  9. Modified Cramer-Von Mises W^2-statistic
  10. Kolmogorov-Smirnov D-statistic (modified for normality testing)
  11. Chi-Square test statistic (equal probability classes) and the number of degrees of freedom
  12. Shapiro-Wilk W Test
  13. Weisberg-Binghams W'' (similar to Shapiro-Francia's W')
  14. Royston's extension of W for large samples
  15. Kotz Separate-Families Test for Lognormality vs. Normality

EXAMPLE

v.random random n=200
v.db.addtable random col="elev double precision"
v.what.rast random rast=elevation.10m col=elev
v.normal random tests=1-3,14 col=elev
computes the sample skewness and kurtosis, Geary's a-statistic and an approximate normal transformation, extreme normal deviates, and Royston's W for the random vector points.

SEE ALSO

v.univar

AUTHOR

James Darrell McCauley <darrell@mccauley-usa.com>,
when he was at: Agricultural Engineering Purdue University

Last changed: $Date: 2011-11-08 03:29:50 -0800 (Tue, 08 Nov 2011) $


Main index - vector index - Full index

© 2003-2016 GRASS Development Team